The production, use, and final disposal of goods are directly linked to various environmental impacts caused along their supply chains and over their entire life cycles. When assessing these impacts for energy‐consuming products such as consumer electronics, not only the emissions caused during production but also the energy consumption during the use phase need to be taken into account in order to provide a holistic view on environmental impacts. However, the interplay between a product's lifetime, reduction of demand through higher durability, energy consumption, and related greenhouse gas (GHG) emissions cannot be generalized but requires very specific analyses, which take into account product‐related aspects and their temporal changes as well as the (changing) properties of the energy and use system. This contribution provides a quantitative assessment of the interrelation between product lifetime and environmental impacts, particularly GHG emissions, using refrigerators and mobile phones as exemplary products with differing characteristics. Whereas in the case of refrigerators, the strongest impact is caused during the use phase because of high energy consumption and related emissions, mobile phones as representatives of classical consumer electronics have their highest environmental impact during production. ... mehrTo assess impacts for both product categories, two simulation models of product life cycles based on methods from dynamic material flow analysis (MFA) are linked with life cycle inventory (LCI) data and LCA results for the respective products, focusing on the impact category of global warming potential (GWP). By systematically evaluating different scenarios, we show major influences on the overall GHG emissions over a product's lifetime capturing temporal developments and modifications within the target system at European scale. In the case of refrigerators, we show that there is a trend towards increasing optimum lifetimes and that current energy efficiency improvements of new devices do not justify early replacement of older devices and, hence, a reduction of service lifetime. This is also because the GHG emissions of electricity production have continuously decreased with an increasing share of renewable energy sources. Regarding mobile phones, we emphasize the counterproductive effect of unused storage time (hibernation) when taking efforts for increasing the service lifetimes aiming at a reduction of demand for new, resource‐consuming devices.